Development of a Pulsed Laser Ablation Technique for the Formation of Carbon Nanotubes

Citation

Abstract / Synopsis

The objective of this work was to develop a pulsed laser ablation technique for the
formation of carbon nanotubes (CNTs). This study was divided into three parts. The
first part involved the development of pulsed laser ablation (PLA) system. The
second part dealt with the growth of CNTs by using the pulsed laser ablation
technique, and finally the last part dealt with the analysis of microstructure and
surface morphology of the deposited sample collected and the influence of the laser
ablation on the surface morphology of the sample target.
A vacuum chamber was designed for the formation of CNTs. The stainless steel
chamber used in this system has a cylindrical shape, with diameter of about 15cm
and 45cm length. CNTs were formed by laser ab!ation using a graphite pellet,
graphite-Ni, graphite-Co and graphite-Ni-Co, each with 10 weight percentage
catalysts. The Nd:YAG laser with 532nrn wavelength, 10.24 W laser power was used
to ablate the target to form the CNTs. Argon (Ar) gas was kept flowing into the
chamber, keeping the pressure inside chamber at 4 Torr.Web-liked CNTs were found in the deposited sample collected after 30 minutes laser
ablation by using the graphite pellet and the graphite filled with mono-catalyst and
bi-catalyst. The XRD pattern for the deposited sample shows the CNTs peak located
at about 26.5". The SEM micrograph show that the diameter size of the CNTs
formed by the Co, Ni, NiCo catalysts and without catalyst follow the order
C>CCo>CNi>CNiCo. The range of the diameters of the CNTs was found to be
about 35-150nm. The sphere-liked carbon structures were found deposited in the
substrate after laser ablation without the Ar gas flowing into the chamber during the
ablation process. TEM micrograph confirmed the formation of CNTs. It was found
that by using a bi-metal catalyst (Ni-Co), a bamboo-like structure of CNTs was
formed.